This invention relates to improvements in a variable valve timing engine which is provided with intake valves whose valve timings are freely controllable so as to regulate an intake air quantity, and more particularly to a system for estimating the intake air quantity when a trouble arises in an intake air quantity measuring device in the variable valve timing engine.
A variable valve timing engine whose valve timings are freely controllable to regulate an intake air quantity has been proposed as disclosed in Japanese Patent Provisional Publication No. 10-37727. This variable valve timing engine is provided in its intake air passageway with an intake air quantity measuring device such as an airflow meter.